The effects of valsartan on laminin (LN), fibronectin (FN), malondialdehyde (MDA), renal tissue fibrosis, and inflammatory infiltration in diabetic nephropathy (DN) rats are explored. A total of 42 SPF male Sprague D (SD) rats are selected and randomly divided into normal set, model set, valsartan low-dose and high-dose sets, and metformin set with 7 rats in each set. The kidney tissue of all rats is collected after administration. The standard of protein mRNA in kidney tissues is detected by real-time fluorescence quantitative polymerase chain reaction (PCR) method, and the protein standard in kidney tissues is detected by western blot. The experimental results show that the application of valsartan to DN rats can effectively relieve the morphology of the rat kidney tissue, enhance the protein expression in the kidney tissue of the DN rats, and reduce the fibrosis and inflammatory infiltration of the kidney tissue.